Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. As technology has progressed, the demand for smaller semiconductor devices with improved performance has increased. As feature densities increase, widths of conductive lines and spacing between the conductive lines of back-end of line (BEOL) interconnect structures also need to be scaled smaller.
A move is being made away from traditional materials used in the past in semiconductor device designs, in order to meet these demands. To reduce an RC time delay, low dielectric constant (low-k) materials are being used as insulating materials, and there is a switch being made to the use of copper for interconnect materials, rather than aluminum. Advantages of using copper for semiconductor device interconnects include abilities to operate faster and manufacture thinner conductive lines because copper has lower resistivity and increased electromigration resistance compared to aluminum. Combining copper interconnects with low-k dielectric materials increases interconnect speed by reducing the RC time delay.
Copper interconnects are often formed using damascene processes rather than by direct etching. Damascene processes are typically either single or dual damascene, which includes forming openings by patterning and etching inter-metal dielectric (IMD) layers and filling the openings with copper. However, there are some challenges in the copper damascene structure, such as adhesion issues between the low-k dielectric material and the underlying layer. The adhesion issues may cause film cracking and/or peeling, therefore, result device package qualification failure.